The purpose of this cooperative agreement is to support a network of sites that provide surveillance and data collection on new vaccine use, the impact of the new vaccines and new vaccine policies through enhanced inpatient and outpatient surveillance, applied epidemiologic research, and investigator-initiated investigations. The research objectives of this program are to 1) evaluate the impact of new vaccines or new vaccine policies on disease in site populations, 2) evaluate the impact of new vaccines or new vaccine policies on administration of other vaccines and 3) understand the burden of vaccine preventable diseases or potentially vaccine preventable diseases in the population. The intent of the NVSN program is to utilize a network of population-based sites to conduct active surveillance for acute respiratory infections (ARI) and acute gastroenteritis (AGE) in addition to providing a framework in which to study other important vaccine related questions. We propose to continue our work in conducting population-based surveillance in Hamilton County, Ohio for acute respiratory infections and acute gastroenteritis to better understand the burden of influenza and rotavirus and to conduct applied epidemiologic studies to examine the impact of influenza and rotavirus vaccines in our community. Proposed studies include vaccine effectiveness studies using case-control and case-cohort methods, determining the cost of rotavirus disease in children hospitalized or cared for as outpatients or in the ED and assessing the background rate of intussusception. In addition, we propose conducting a series of complementary studies in collaborating pediatric practice networks to assess the impact of new vaccines on immunization providers. Specifically, we will evaluate the impact of new vaccines on immunization coverage levels and the number of injections administered per up-to-date child, provider knowledge, attitudes, intentions, and self-reported practices regarding use of new and combination vaccines and the cost impact of new vaccines on pediatric practices and their immunization delivery. We have provided evidence of our extensive experience developing surveillance systems in both the hospital and emergency department at Cincinnati Children's Hospital Medical Center (CCHMC) and our ability to work effectively within our community with health care providers and public health agencies as well as collaboratively with the existing NVSN sites and the CDC. We are thus in a unique position to provide the extensive services and expertise required in this application. The NVSN will address a number of priority areas in the Healthy People 2010 objectives. The infrastructure of such a network along with carefully planned research activities utilizing population-based enhanced surveillance and computerized databases with disease and immunization histories will provide the data needed to examine progress towards meeting the Healthy People 2010 objectives. Immunization and infectious disease issues are a top priority in the US as described in Healthy People 2010 objectives. Several of these objectives such as the reduction or elimination of vaccine preventable diseases (objective 14-1) and the evaluation of vaccination coverage for universally recommended vaccines (objective 14-22), are addressed in this application. Population-based surveillance will assess the disease burden of specific infections while applied epidemiologic studies assessing vaccine coverage will identify barriers to good coverage. Providing accurate rates of intussusception (IS), a potential adverse event of rotavirus vaccine is also addressed in this application (objective 14-30).